Electronically graded composites

Electronic-Grade MMCs. Metal-matrix composites can be tailored to have optimal thermal and physical properties to meet requirements of electronic packaging systems, eg, cotes, substrates, carriers, and housings. A controUed thermal expansion space tmss, ie, one having a high precision dimensional tolerance in space environment, was developed from a carbon fiber (pitch-based)/Al composite. Continuous boron fiber-reinforced aluminum composites made by diffusion bonding have been used as heat sinks in chip carrier multilayer boards. 

A distillation process is shown in Fig. P2.59. You are asked to solve for all the values of the stream flows and compositions. How many unknowns are there in the system How many independent material balance equations can you write Explain each answer and show all details whereby you reached your decision. For each stream, the only components that occur are shown below the stream. Metallurgical-grade silicon is purified to electronic grade for use in the semiconductor industry by chemically separating it from its impurities. Si metal reacts in varying degrees with hydrogen chloride gas at 300°C to form several polychlorinated... 

RTX366. [l one-Poulenc] Supercooled liq. cyanate ester monomer for large aircraft composite structures, micro-wave antennas, radomes, spaceware, and structural or electronic grade adhesives. 

In addition, mixed semiconductors with graded compositions have, as described earlier relevant to gradations due to pressure, graded electronic properties for example, graded band gaps. A graded mixed crystal explosive should have predictable, nonsteady-state, detonation characteristics. The nonsteady time dependence and partial directionality of the detonation may be of interest. 

J. E. Sutherland and J. R. Hauser, A computer analysis of heterojunction and graded composition solar cells, IEEE Trans. Electron Devices ED-24 (1977) 363-372. 

Carbon is also the main material used for BP. As in the case of GDLs, metals were also used in the fabrication of BP perhaps with more extent than with the GDL. Carbon as material for BP is used mainly as graphite block (electronic grade graphite) or as a carbon-polymer composite, although some other forms have been tested [124]. 

Nakano and Jimbo investigated the interface electronic properties of thermally oxidized n-type GaN metal-oxide-semiconductor (MOS) capacitors [230]. The formation of an intermediate gallium oxide nitride layer vith a graded composition could provide the origin of a small capacitance transient observed experimentally. 

A close inspection of Fig. 1.18 shows also weak diffraction spots marked by A , B and C , corresponding to a composition grading portions of the Sii-yGCx layers with Ge composition 4.60 ( A ), 7.52 ( B ) and 11.45 at.% ( C ), respectively. The graded composition in this layer was also confirmed by electron diffraction scans using transmission electron microscopy on the same samples. 

S. C. Choo, Theory of a forward-biased difhised-junction p-i-n rectifier—Part 1 Exact numerical solution, IEEE Trans. Electron Devices ED-19 (1972) 954-966. J. E. Sutherland and J. R. Hauser, A computer analysis of heterojunction and graded composition solar cells, IEEE Trans. Electron Devices ED-24 (1977) 363-372. 

In addition to bilayered electrodes with a functional layer and a support layer, electrodes have also been produced with multilayered or graded structures in which the composition, microstructure, or both are varied either continuously or in a series of steps across the electrode thickness to improve the cell performance compared to that of a single- or bilayered electrode. For example, triple-layer electrodes commonly utilize a functional layer with high surface area and small particle size, a second functional layer (e.g., reference [26]) or diffusion layer with high porosity and coarse structure, and a current collector layer with coarse porosity and only the electronically conductive phase (e.g., reference [27]) to improve the contact with the interconnect. 

---